Stabilization of fuels containing tetraethyl lead



United States Patent Ofiice g 2,869,995 STABILIZATIUN F FUELS CONTAINING TETRAETHYL LEAD Josef M. Michel and Karl F. Eager, Fort Bliss, Tex.,

assignors to the United States of America as represented by the Secretary of the Army No Drawing. Application July 18, 1950 Serial No. 174,567

28 Claims. (Cl. 52-.5) ,(Qranted under Title 35, .U. S. Code (1952), see. 266) The invention described in the specification and claims may be manufactured and used by or for the Government a p er m P o e w t qn t e tan o 11 5 of any royalty thereon.

it is known that tetraethyl lead either pure or mixed other compounds and even when highly diluted as leaded gasoline is not stable for any great period 9 t i e m o es ,esneq a when e p t light or moisture, catalytica lly forming lead oxides and/ or lay- Fi P l f qui me gam n i .QQ J QSE i h th e decomposition products is built from copper, brass, stain less steel, nickel or nickel alloys, no harmful reactions "will take :place. However, if light metals or their alloys are used in building such equipment, difliculties will arise under conditions prevailing in practical use.

By experience it has been proven that fuel containers made of light metals or their alloys, in particular those made of magnesium or magnesium alloys, will become perforated within a very short time when in contact with liquid fuels (e. g. gasoline) containing tetraethyl lead. Scientific investigations of this problem have lead us to the following explanations of the cause of the perforation of the containers: As long as the water content of theli quid fuel is lnelqw solubility limit o f water in tl efueh tliereis no danger tha ,such a foigma tion of holes will take pla e "Hat v n if the Po a i reach d when t water is o issalv tanke 12 9 liqu d fue bu earner a e' sen 9 senate ag fe ex ale a the o m f such a annin t e sqtnnes tion re.- actionmentioned above will start, H eventually small holes passing family through the lls of the container M ts, a a. M n 0 d sx s ss s mrpae t ha in a hi h speci flcg ravity sink to the .bo ttomof the container where an t n in an I f the a the a ant bu up ,alocal element of which the lead compound is the e ei a i h as i ma ay th i nasleh -means that the metal of 'thecontainer" will dissolve. At every place where the decomposition products of the t etraethyl lead ,come in contact with'thecontainer walls, such an electrolytic corrosion starts. According to conditions, it may ,takeonlyla very short time to produce perforations in the container. Tests have shown that the holesformed appear. The .tetra ethyl lead decomposes at themce between the fuel and water, forming leadoxides by this electrochemicaltprocessiareiusually foundin the water phase or at the interface ,hetween liquidfuel water. T e same is true for 95111211121 other metals, for example, aluminum, iron, zinc, all oys of aluminum, and certain alloys of iron and of zinc, even ,if the special place of these metals and alloys in the electr oinotiye series results in a slower action.

We have discovered that the abovedescribed decomposition of tetraethyl lead and the perforation of metal containerfor liquid-fuels containing tetraethyl lead can beprevented byapplying-to the interior wall or walls of the containers or by incorporating in or mixing with the liquid fuel, a hydrocarbon (a1kyl)-sulfamido cartboxylic acid or an inorganic or organic salt thereof.

.R,SO,-NHR COOH in which R, is an alkyl radical, of at least five carbon atoms, and 2 an lkY aQ Pa SS qs khyd s e In other words R isa divalent ali haticradical o general formula C H having one yalency b o d nected with the carbon atomof thecarboxylg dl p 35, another valency bond connected with the nitrogen atom f th R1S 2NH ro a- .1R1 i nte ra rv an tatlical of from 12 to 1,3 carbonatoms inclusive, either of the straight chain or branched chain type, but pi efera y o t S r g ch t p Ex rls o hydr ca bonsnlfarnido-carboxylic acids, whi may be used inlthe P a ice of h p s nt inven i n re d oca bon 1248)- ;5fig fi fli hy fi ifib hi-16)" sulfamido-acetic (sometimes ifeferred to as mepaisiniam d a i acid) tqe y sglta id t ri C8H1'7SO2 'N 3 6 tetradecyl-sulfan rido propionic acid,

tqtHas ze nczntc on and hexadecyl-s nlfamido-acetic acid,

taHa 159a -In a broader .sense the "hydrocarbon-sulfamido-carboxylic acids ,that may be used the practice of the present invention ,are, ,or may be regarded as derivatives of 'the lower fatty or aliphatic ,acids of .the general formula C l-l O such as formic acid .(HCQOH), acetic acid, CH CQOH, ,propionic :acid 1(=C H COOI]IL) and butyric ac d, 3 5GQ0H, in which a hydrogen atorn ,theieof attached to .a carbonatom has been replaced by the univalent group *NHSO 'H ;R being .an alkyl radical of the rmmber of carbon atoms defined; The correctness of this view point arises from the fact that theliydroearl;on-sulfamido-carboxylic acids under consideration may beprepared from ,monorchlor aliphatic acids by reaction with compounds of the type R SO NH with liberation of hydrogen chloride arising from one hydrogen 4 1 9 th am ne rou (N112) RISO-ZNHZ uniting thelchlorine atom oflthet mono-chlo'r aliphatic acid; As the chlorine atom of the nionorchlor aliphatic acid replacedia hydrogen atom of ,the aliphatic acid, and since in the compounds under consideration the ,TNHSO R group replaces the chlorine atom, the net result is, in effect, a replacement of a hydrogen atom ,(attached to a caibo n atom) of the aliphatic acid by the NHSO R group. The'descr'ibed reaction may be conducted in the presence of an alkali, for example' sodium or potassium hydroxide, whereby thecorresponding salts of the hydro a en-sul amis a a b ayli a i a ta li iamplesof salts of hydrocarbon sulfamido-carboxylic acids that may be used in practicing the invention are: inorganic salts snchasjslodium, potassium and ammonium salts, an dsalts of ammonia derivatives such as hydrazine; and organic salts such as salts ofcyclohexylamine, methylan ine and ethylamine.

:Ihe action of these compounds i s ,based on ,two funam ta eqt .(fl) ;Stahi ns e fect On the r h l lead itself by inhibiting the decomposing forces of the humidity andthe surface tension ,between the two phases he r d randlb) f a iq 9 mole u c a on the inside wall of the container that insulates the metal or alloy against the decomposition products of the tetraethyl lead, when formed occasionally, whereby any formation of local elements is prevented.

From the different actions and reactions: necessary to satisfy th se irequirements and :from the facts observed in practical use, it is easily seen that only such com- 2 The sad 3 poundswould be able to give a good and reliable protection against these electrochemical reactions that have a stabilizing effect on the lead compound and in addition a very high aflinity with respect to the metal in order 'to be able to form films that are firmly bonded to the surface, tight, and that can not be damaged by liquid fuels, water, or diluted saltssolutions.

, ln spite of ,the fact that protective coatings consisting of such metal activecompounds can easily be produced by treating the metal parts with either water emulsions or organic solutions containing up to 50% hydrocarbon-sulfamido-carboxylic acids and/or their inorganic or organic salts, the simplest way and technically easiest to handle is the addition of small amounts ,(below 1%) of the compounds mentionedto-the liquid aseaaes ill fuel's,-'f'water and diluted salt; By this method, not only the tetraethyl lead is stabilized reliably but also a pro- :tective coating is formed and even restored when damaged, e. g.,' by mechanical forces. Finally, the surface tension is decisively changed between the two separate phases, fuel and water, when formed. This simple methodbe'comes'possible owing to' the fact that the metal active compounds are not only soluble in the organic or liquid fuelmedium but also in Water. It is known that some proposals have been made to use mepasin"-sulfamido-acetic-acid-sodium salt as an inhibitor for fuels. From these proposals it could not be learned, predicted or foreseen at all that the process claimed and described in this application would have any stabilizing effect on tetraethyl lead and could par- .alyzethe dangerous-action of :any decomposition products by forming tight coatings on the metal surface.

Furthermore, no one could expect or be able to calculate theoretically in advance that a water phase originating from a fuel that contains only small amounts of hydrocarbon-sulfamido-carboxylic-acids and/ or their inorganic andorganic salts would dissolve any amount of metal active compound sufliciently to guarantee a reliable stabilization of the tetraethyl lead and the formation of a tight protective coating on the metal or alloy in question.

Experiments carried out as well as the methods used for proving the utility of the procedure and their results are given below:

Example No. 1

- Welded containers made of a magnesium alloy consisting of 6.5% Al, 1.0% Zn; 0.2%, Mn; rest, magnesium. One of these was filled with a water emulsion containing 25% hydrocarbon (C )-sulfamido-acetic acid sodium salt at ambient temperature. After a few minutes the tank'was empited and then refilled with leaded gasoline (octane number 82). After two weeks storage, as no change in the condition of the inside walls had occurred,

tap water was added in such an amount (about 1%) that a second phase'was formed on the bottom of the tank. Test conditions were changed from time to time by shaking the container on a plate feeder; and by outdoor and indoor storage to get the changing ambient temperatures between day and night time. A careful check after a test period of 6 months showed no formation of local elements, either in the water or in the fuel phase, which means that the tetraethyl lead has been stabilized. In contrast, another container, same size and alloy, tested under the same conditions, but without the above described emulsion treatment -showed first spots of local elements after two weeks, and after two months,'it was perforated. The holes, which were substantially of microscopic size, were mostly found in the water phase, a few of them at the interface between fuel and water.

Example N0. 2

ethyl alcohol at ambient temperature. After allowing the excess solution to drain out of the tank, it was filled with aviation gasoline octane) containing tetraethyl lead and treated in the same way as mentioned for the magnesium container in Example No. 1.

While the sprayed container was entirely unchanged as to the conditions of the inside walls because of the stabilizing effect of the compound mentioned, untreated tanks showed serious corrosion symptoms caused by formation of local elements after 4 weeks only.

Example N o. 3

Ordinary iron strips, welded, 5 x 2.5 x 0.05 inches, were put in leaded gasoline (75 octane) containing 0.05% tetra-decyl-sulfamido-propionic acid cyclohexylamine salt first, without an'd later on, with water forming a second phase on the bottom of the glass jars that were usedforthese test series. By the stabilizing effect of this compound, the results, after a period of 10 months, were excellent showing no difference on comparing the appearance of the specimens before and after storage in the leaded gasoline. On other test pieces, however, in contact with unstabilized leaded gasoline, formation of local. elements could be observed appearing in rust spots, a few days after the addition of water. This reaction spread over the whole surface, first in thewater, and later in the fuel phase also. After 3 months of testing by partially storing, and partially shaking, the following corrosion results were obtained:

Water phase 350 g./m Fuel ph g./m

In comparison, the other specimens in the stabilized fuel, showed the corrosion results:

Water phase 0.1 g./m 7 Fuel phase 0.05 g./n 1

which means an improvement ratio 1:3500.

Example N0. 4

use, the fuel was changed every week. In addition,'the

inside wall was slightly brushed in order to remove some deposits from the bottom of the container. While no formation of local elements could be observed during 1 the first month of testing, the stabilizing effect caused by the hydrocarbon-sulfamido-carboxylic-acid film decreased remarkably afterwards, and 10 days later (about 40 days after starting the test) formation of local elements followed by electrochemical reactions had already started at several places.

In order to avoid these difficulties it was found that it is sufiicient to add small amounts of the metal active compound in question to the fuel. By doing so, it was observed not only that the decomposition of the tetraethyl lead was stopped but also that the damaged coating was restored at once, even if the weak spots were situated in the water phase.

According to this result, other containers, same shape and alloy, were handled in this way, that 0.05% hexadecyl sulfamido acetic acid potassium salt were added to the test gasoline and then the same test procedure. was observed as mentioned above. Even after a period of 8 months, all the containers were in excellent condition and not a single spot of attack caused by deposit of lead oxides on the inside wall, especially in the water phase or at the interface between fuel and water, could be fmmrl,

Example -N0. -5

with different fuel mixtures containing .tetraethyl lead with and without addition of hydrocarbon (C sulfarnido acetic acid sodium salt. ,It was found that only when using emulsions or solutions of the metal active compounds mentioned for the pre-trea trnnt of the system or by addition of small amounts (below 1%) of those chemicals to the fuel or fuel mixtures in question, it was possible by stabilization of the tetraethyl lead to avoid any chemical or electrochemical action with the feeding system. This is especially true when the feeding system was cleaned mechanically and rinsed with water between two test runs in order to remove fuel residues.

, In all other cases, using fuel compositions without additional admixtures of stabilizing and metal active compounds like hydrocarbon sulfamido carboxylic acids and/or their inorganic and/or organic salts formation of local elements or electrochemical reactions started after a short time, especially on the light metal parts which are more endangered according to their position in the electromotive series.

With fuels and fuel mixtures containing even very small amounts of the metal active compounds mentioned above, it was possible to operate such systems for months without any trouble in spite of the fact that not only the fuels and fuel mixtures but also the structure and assembly of the whole equipment were changed several times, according to the special demands of the tests in question.

We claim:

1. The method of protecting a metallic surface exposed to contact with a fuel composition consisting of a watercontaining gasoline carrying tetraethyl lead, said fuel composition being normally corrosive to said metallic surface, which comprises supplying to said metallic surface from 0.05% to an amount below 1% of a stabilizing agent dispersed in gasoline, said stabilizing agent being selected from the group consisting of an organic compound having the formula in which R is an alkyl radical of from 5 to 18 carbon atoms and R is a lower aliphatic radical of the general formula C H where n is a small positive integer, and the salts of said organic compound taken from the group consisting of sodium, potassium, ammonium, hydrazine, cyclohexylamine, methylamine, ethylamine and mixtures thereof, and acting on said metallic surface with said stabilizing agent to stabilize and protect said surface against the corrosive action of said fuel composition.

2. The method according to claim 1 wherein the stabilizing agent is mepasin-sulfamido-acetic acid sodium salt.

3. The method according to claim 1 wherein the stabilizing agent is octyl-sulfamido-butyric acid ammonium salt.

4. The method according to claim 1 wherein the stabilizing agent is tetradecyl-sulfamido-propionic acid cyclohexylamine salt.

5. The method according to claim 1 wherein the stabilizing agent is hexadecyl-sulfamido-acetic acid potassium salt.

6. The method according to claim 1 wherein the stabilizing agent is a sulfamido-acetic acid sodium salt of a saturated hydrocarbon.

7. The method according to claim 1 wherein the supplied stabilizing agent is in amount in excess of that required to stabilize the metallic surface, and the surface is subsequently contacted with a gasoline fuel containing tetraethyl lead.

8. The method of protecting a metallic surfaceexposed to contact with a fuel composition consisting of a water-containing gasoline and tetraethyl lead, said fuel composition being normally corrosive to said metallic surface, which comprises supplying to said metallic surface a stabilizing agent dispersed in an inert solvent, said stabilizing agent being selected from the group consist ing of an organic compound having the formula in which R is an .alkyl radical of from 5 to 18 carbon atoms and R is a lower aliphatic radical of the general formula C fl where n is a small positiveinteger, and the salts of said organic compound .taken from the group consisting of sodium, potassium, ammonium, hydrazine, cyclohexylamine, methylamine, ethylamine and mixtures thereof, said stabilizing agent being present in said inert solvent in from0.05% to an amount below 1%.

9. A method of protecting a metallic surface exposed to contact with a fuel composition consisting of water, ethyl alcohol and leaded gasoline, said fuel composition being normally corrosive to said metallic surface, which comprises supplying to said metallic surface a stabilizing agent dispersed in said fuel composition and constituting from 0.05% to an amount below 1% thereof, said stabilizing agent being selected from the group consisting of an organic compound having the general formula in which R is an alkyl radical of from 15 to 18 carbon atoms and R is a lower aliphatic radical of the general formula C I-I where n is a small positive integer, and the salts of said organic compound taken from the group consisting of sodium, potassium, ammonium, hydrazine, cyclohexylamine, methylamine, ethylamine and mixtures thereof, and acting on said metallic surface with said stabilizing agent to stabilize and protect said surface against the corrosive action of said fuel composition.

10. The method according to claim 9 wherein the stabilizing agent is mcpasin-sulfamido'acetic acid sodium salt.

11. The method according to claim 9 wherein the stabilizing agent is acetyl-sulfamido-butyric acid ammonium salt.

12. The method according to claim 9 wherein the stabilizing agent is tetradecyl-sulfamido-propionic acid cyclohexylamine salt.

13. The method according to claim 9 wherein the stabilizing agent is hexadecyl-sulfamido-acetic acid potassium salt.

14. The method according to claim 9 wherein the stabilizing agent is hydrocarbon sulfamido-acetic acid sodium salt.

15. The method according to claim 9 wherein the supplied stabilizing agent is in an amount in excess of that required to stabilize the metallic surface and the surface is subsequently contacted with said fuel composition.

16. A composition of matter consisting essentially of leaded gasoline carrying water and from 0.05% to an amount below 1% of a stabilizing agent dispersed in an inert solvent, said stabilizing agent being taken from the class consisting of an organic compound having the formula R SO NH-R COOH in which R is an alkyl radical of from 5 to 18 carbon atoms and R is a lower aliphatic radical of the general formula C H where n is a small positive integer, and the salts of said organic compound taken from the group consisting of sodium, potassium, ammonium, hydrazine, cyclohexylamine, methylamine, ethylamine' and mixtures thereof.

17. A composition according to claim 16 wherein the stabilizing agent is mepasin-sulfamido acetic acid sodium salts.

18. A composition according to claim 16 wherein the stabilizing agent is octyl sulfamido-butyric acid ammonium salt.

. 19. A composition according to claim 16 wherein the stabilizing agentis tetraethyl-sulfamido-propionic cyclohexylamine salt.

e '20. A composition according to claim 16 wherein the stabilizing agent is hexadecyl-sulfamido acetic acid p0- tassium salt.

21. A composition according to claim 16 wherein the stabilizing agent is a sulfamido-acetic acid sodium 'salt of a saturated hydrocarbon.

22. A fuel consisting essentially of gasoline, tetraethyl .lead and from 0.05% to an amount below 1% of an added compound selected from the group consisting of an. organic compound having the general formula in which R is an alkyl radical of from 5 to 18 carbon atoms and R is a lower aliphatic radical of the general formula C H where n is a small positive integer, and the salts of said organic compound taken from the group consisting of sodium, potassium, ammonium, hydrazine,

cyclohexylamine, methylamine, ethylamine and mixtures I thereof.

25. The fuel of claim 22 in which the added compound is tetradecyl-sulfamido-propionic acid cyclohexylamine salt. a 4

26. The fuel of claim 22 in which the added compound is hexadecyl-sulfamido-acetic acid potassium salt.

27. The fuel of claim 22 in which the fuel contains water.

28. The fuel of claim 22 in which the added compound is a sulfamido-acetic acid sodium salt of a saturated hydrocarbon.

References Cited in the file of this patent UNITED-STATES PATENTS Meyer Dec. 19, 1939 2,183,856 2,578,725 Michel et a1 Dec. 18, 1951 2,680,066 Michelet a1 June l, 1954 

22. A FUEL CONSISTING ESSENTIALLY OF GASOLINE, TETRAETHYL LEAD AND FROM 0.05% TO AN AMOUNT BELOW 1% OF AN ADDED COMPOUND SELECTED FROM THE GROUP CONSISTING OF AN ORGANIC COMPOUND HAVING THE GENERAL FORMULA 